Apparatus for making seamless tooth-crowns.



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(Application tiled JLn. 9, 1900.)

" UNITED STATES PATENT OFFICE.

JOSEPH FRANKLIN TWIST,'OF SAN FRANCISCO, CALIFORNIA.

APPARATUS FOR MAKING SEAM LESS TOOTH-CROWNS.

SPECIFICATION forming pari-,vof Letters Patent No. 660,319, dated October 23, 1900.

' Application filed January 9, 1900. Serial No. 877. No model.)

To all Lil/1,0m, it may concern:

Be it known that LJosEPH FRANKLINTWIST, a citizen of the United States, residing in the city and county of San Francisco,State of Cali fornia, have invented an Improvement in Apparatus for Making Seamless Tooth-Crowns; andI hereby declare the following to be a full, clear, and exact description of the same.

My invention relates to an apparatus for the manufacture of seamless tooth-crowns.

It consists in a mechanism for forming the crowns and a means for tting and adapting them to the position in which they are to be used.

It also comprises details of construction, which will be more fully explained by reference to the accompanying drawings, in which Figure l is a vertical section of a base, die, and gide with a punch. Fig. 2 is a horizontal section of adjustable guide through m Fig. 3. Fig. 3 is a vertical sectional view of the same, partially in elevation. Fig. 4 is half of flask with moldine and castor pattern. Fig. 5 shows the other half of ilask empty. Fig. 6 shows half of metal cast with pattern embedded. Fig. 7 is a vertical section of inal former.

In the formation ci )what are known as seamless tooth-crowns it is first necessary to make the crown from a disk of gold. This is generally eected by forcing the disk through successive holes in a die-plate, by which the rim or flange is gradually turned up around the central portion until the proper size has been produced. The rst part of my invention relates to an improved mechanism for performing this work at a minimum of labor and expense.

As shown in Fig. l, the base A has a central hole countersunk to receive the die 2, which is fitted therein. This die has a hole made through it, the upper edge being beveled so as to prevent its breaking or tearing' the metal of the disk which is to be forced through the die. These dies fit loosely into the central socket, and any number of them may be fitted to the same socket, the interior of each being successively smaller than the preceding one, so that by continuously forcing the disk and the crown which is being nformed from it through these decreasing dies the sides will be turned up and the diameter of the whole crown decreased until it reaches the desired size. In order to effect this, it is necessary to have punches 3, which iit each of the various dies 2 used. These punches are formed upon the lowerend of a shank 4, which shank is always maintained of a certain diameter in all the punches.

5 is a guide through which the shank 4 is slidable, this guide being of sufficient diameter to receive and direct 4 when the punch 3 is forced down through the die 2. The guide 5 has at the bottom a circular rim or flange which iits into a correspondingly-shaped depression in the top of the stand or support A. This maintains the guidecentral and with its own axis in line with the axes of the various dies which are used during the operation. With this constructionit is only necessary to reduce the lower portion 3 of each punch to .correspond with the die with which it is to be used, While the upper portion el remains of the same size in all of the punches, so that they all fit the single guide 5. In order to still further reduce the expense of the punches, each punch may be made of a single bar or rod having the same diameter throughout its length. In this case the guide consists of the outer cylinder 5 fitting the stand A, as before described, and having the central opening coincident with that of the dies 2. Within this outer cylinder are the radiallydisposed vertical wings 6, movable in slots in the body of the casing, and these wings are normally retractedin the slots by a spring or springs 7. The upper and lower ends of the casing 5 are closed by caps having the eccentric or cam-shaped shallow grooves or channels 8 made in them, into which the 'upper and lower ends of the wings 6 extend,

as shown in sectional view, Fig. 3. The slotted central body in which the wings are carried is turnable within the outer casing 5 by means of a projecting pin 9, which extends outwardly through a groove or slot 10, made circumferentially through the side of the outer casing 5. l pin the inner body and the wings are turned within the outer casing, the upper and lower ends of the wings in contact with the cam- Wlien by means of this IOO diameter.

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shapedgrooves 8 will be eitheradvanced-.or retracted in unison as they areturned in one direction or the other.

A scale may be marked along the slot 10 with figures indicating the size of punch that isto be used when t-he devicehas been tu rned to any particular figure. 'ihus when turned so that the wings are retracted to their fullest,K extent the largest-sized punch may be used,'

and the disk which is to be formed into a tooth-crown being laid upon the die 2 the punch is pressed or driven down uponit, and it will be forced through vthe die anda peripheral flange turned up. A die of the next smaller size being then placed in position, the corresponding punch isselected, 'and by turning the wings to the next figure they will be moved toward each other, thus forming aguide which will receive the next `smaller-sized punch, kand the operation is.l -thus repeated until thecrown is of theI properk By the use of this device the cost of punches is materially reduced, since they need be only simple straight rods and the guide-wings can be adjusted to suit any size which is to be driven through.

The die, which is formed to-correspond with the tooth, is made-by taking a fiask formed in two sections 11 and 12, with tongues4 and grooves which cause them to register properly Whenplaced together, and-pressing a. yielding material called moldine into the chamber formed in one of the halves. Apreviously-prepared plaster-of-paris cast 13, having the exact form desired, is then pressed into this material until one-half of it is embedded. The two parts are then put together andthe half which has not been filled with the molding material is filled with asuitable fusible metal which flows around the half of the cast which has not been embedded in the moldine. When this is suficientlycool, the ask isseparated and the moldine is removed from the half which it occupied, thus leaving the other half of the cast projecting from the metal with which one side has been llecl. -Soapstone or any suitable material being spread over the surfaces toA` prevent undue ad-` herence, the ask is then put together and fusible metal poured into the half-previously occupied by the moldine, thus entirely sur.

roundingthe cast and forming a two-,part matrix 14 when the cast has been removed.

-This is done by separating the parts of the. mold and the two metal sections 14,-whic`h have been cast within'it, and this leaves a, -xnatrix, which is afterward filled up with fusible metal, precaution being taken to prevent its adherence to the matrix, and this being completed is then ready for the application and fitting of a tooth-crown. A suitably sized and shaped crown being selected,`

it isplaced over the .end of themetallic die 15 whichlhas been formed, and thelatter is then replacedinto the metal matrix 14=and the parts again fitted together.

The outside of the matrix 14 thus formed is made slightly shaped and fitted to the die. afterward removed by fusing it, and the `tapering by the shapelofthe hollow mold in which the two parts have been cast, and it is then inserted into a sleeve 16, having a cor- 7o respondingly-shaped conical interior to receive it. The outside of the part 16 is screwthreadedfand a cap 17 ,having corresponding screw-threads and handleslS, by which it isturnable, is fitted to turn upon the part 16. Before applying this, however, a concave-faced pressure-block 19 is fitted into the interior of the cap 17, and this block has@ ypin 20, which projects up through a corre sponding-centralhole in the top of the cap 8o 17. The concaved face rests upon the outer end of the metallic die 15 previously described, and when the screw-cap 17 is turned down the part.19, pressing.upon.theprojectingfend of lthe metallic die 15, forces it downward, so as to 8 exactly shape the top of the tooth-crown to fit the endy ofthematrix. At the same time by reason of the conical shape of the interior ofthe part-16 the forcing of .thetwo-'part mold or matrix 14 into this cone will compress it traus- 9o versely, and the crown will thus be perfectly Theflatter is crown isleft in perfect shape and adapted to the position where it is to be applied. Having thus described my invention,.what I claim as new, and desire to secure by'Letters Patent, is"

1. In an apparatus for forming seamless tooth-crowns, a device forprimarily shaping roo 4the crowns consisting of a series of dies, and

,means adapted to fit saidguide to any size of Apunch.

.3. In a device for forming seamless toothcrowns, a die-supporting stand, aseries of dies, punches correspondingin diameter with :zo .the dies, a variable guide fitting the stand concentrically with the dies, consisting of radially-sli'dable guide-wings between which thepnnch is movable andmeans for varying the distances of said wings from the center.

4. A device for forming seamless toothcrowns consisting of a die-supporting stand,

a series of dies,.punches fitting the dies, a

lguide .consisting of radially-movable wings slidablein grooves-or channels ina casing, 13o

.springsby which said wings are normally retracted, .and cams by which the wings may be advanced to fit and guide any size of punch. 5. In a device for forming seamless toothcrowns, a die-supporting stand, a series of dies, punches fitting the various-sized dies, a casing having a radially-slotted central portion, wings slidable insaid slots and springs by which they are normally retracted, beads fitting the upper and lower ends of the casing having cam-shaped chambers into which the upper and lower ends of the Wings project, and means for turning the wing-carrying center with relation to said cams, so that the wings are advanced or retracted.

6. in a device for forming seamless toothcrowns, a die-supporting stand, a series of dies, a punch-guideconsisting of an exterior casing fitting the stand concentrically with the dies, the central portion turnable Within the casing, a pin projecting through a slot in the casing by which it is turned, radial slots hand. j

JOSEPH FRANKLIN TWIST. Witnesses:

S. H. NoURsE, JESSIE. C. BRODIE. 

